This invention relates to electronic display device, for example an electronic timepiece for use in motor cars, wherein the number of the operating switches is reduced.
In recent years, digital type electronic display devices utilizing quartz such as electronic timepieces have been widely used for motor cars. Considering an electronic timepiece as an example, the timepiece is constantly driven by receiving a driving current from a battery, but for the purpose of decreasing the power consumption of the battery, a display device of the timepiece which consumes relatively large power is operated only when the accessory contact or an ignition contact of an engine key switch is closed. For this reason, it has been impossible to know the time displayed by the timepiece when these contacts of the engine key switch are open or when an engine key is removed from the engine key switch.
For this reason, a time display device has been proposed wherein an independent manually operated switch is provided for the timepiece so that when this switch is closed, the time is displayed for a definite interval even when the engine key switch is open.
In such a display device, however, it is general to further provide independent manually operated switches for selecting additional display functions (added to a normal display of the time) of the device with the result that the operation panel requires a large area and becomes complicated, raising the production cost and impairing the appearance and ease of operation. Especially, in a digital electronic timepiece which is provided with many correction knobs, problems raised by the addition of separate manually operated switches are aggravated.